Method and apparatus for drying of moisture-setting inks



Feb. 7, 1967 R. H. HOLMWOOD ET L METHOD AND APPARATUS FOR DRYING OF MOISTURE-SETTING INKS Filed Aug. 14, 1964 FIG. 1

2 Sheets-Sheet 1 INVENTORS RICHARD H. HOLMWOOD HANS J. HUTH ATTORNEY Feb. 7, 1967 MW mp 3,302,296

METHOD AND APPARATUS FOR DRYING 0F MOISTURE-SETTING INKS Filed Aug. 14, 1964 1 2 Sheets-Sheet 2 3,302,296 METHOD AND APPARATUS FOR DRYING F MOISTURE-SETTING INKS Richard H. Holmwood, Binghamton, and Hans J. Huth,

Vestal, N.Y., assignors to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed Aug. 14,1964, Ser. No. 389,565

. 4 Claims. (Cl. 34-9) This invention relates to the drying of moisture-setting inks, and more particularly to a pressure dampening system for drying moisture-setting printing inks.

An object of the invention is to provide a new and improved method and apparatus for increasing the drying rate of moisture-setting inks.-

Another object is the provision of a new and improved method and apparatus for. adequately drying heavy ink films with an increase in productive capacity.

. Yet another object is to provide a generally improved United States Patent 0 and more satisfactory ink drying system for use on a high speed press operating on a continuously moving web of material I A further object is the provision of an improved and more eflicient rotary card making press for printing and cutting to size unit record forms such as are used in business and data proce's'sing'machines.

The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of a preferred em bodiment of the invention, as illustrated in the "accomand a partial edge view of the web after emergence from this station.

'The rotaryv card manufacturing machine of which a portion is illustrated in FIG. 1 is described more completely in US. Patent No. 2,181,935 to F. M. Carroll dated December 5, 1939. The machine operates on a continuous web of fibrous cardstock material to print record forms thereon which are subsequently cut apart into unit card lengths, each with a printed form. The unit record form manufactured in this manner is the familiar tabulating card or punched card used in business and data processing machines. Only so much of the rotary card manufacturing machine is illustrated here as is essential to an understanding of the invention.

A web 11 of fibrous cardstock material pre-cut to the desired width unrolls from a supply roll not here shown.

After passing between feed or idler rolls13, 13', the Web 11 travels vertically upwardly between print rolls 15, 15 forming a portion of the print station 17. The web .11 at this point is printed on both sides since the print station 17 includes a mirror image set of rolls on either 7 "ice cards 29. The individual cards pass upwardly between fluted rolls not here shown and are clipped to the periphery of a rotary carrier wheel 31 for carrying the cards to the other side before being released for stacking in a finished pile.

The type of printing performed at the print station 17, be it letterpress or ofiset, including dry offset, is immaterial to the invention. Offset printing is here illustrated and is performed for instance by a pair of inking rolls 33 which apply ink to an offset roll 34, this roll in turn being in engagement with the print roll 15 for transferring the impression to the web I11. In general it can be said that a suitable moisture setting ink is used. Upon leaving the print station 17, the ink on the printed web is in a wet condition.

The ink drying station 21 includes, in addition to the pressure roll 19 previously mentioned (only one side will be described), a dampening roll 35, a metering roll 37, land a spray applicator 39. The dampening roll 35 is covered with a soft moisture retaining material 41 such as molleton, soft rubber, a knitted sleeve or the like. Moisture is conveyed from a supply reservoir not here shown through a pipe 42 to the spray applicator 39 whose stream impinges directly on the moisture retaining cover 41 at the nip. The metering roll 37 has a hard hydrophilic surface and is mounted for adjustment to and from the center of the dampening roll 35 to regulate the amount of moisture retained by the cover 41. The surface of the pressure roll 19 is in contact with the cover 41 of the dampening roll and is coated with a thin film of moisture therefrom. The surface of the roll 19 is hydrophilic in order that the film of moisture thereon is spread evenly over its entire surface without the formation of droplets.

The effect of passing the printed web 11 between the dampened pressure rolls 19, 19' can be seen by comparing FIGS. 2 and 3 wherein a typical cross section of the thickness of the cardstock is illustrated. On a microscopic'scale the surface of the web 11 can be likened to aseries of hills and dales. Upon leaving the print station 17, after passing between the print rolls 15, 15', ink 43 in wet condition is deposited on the surfaces of the cardstock on or near the fiber peaks. Upon leaving the ink drying station 21 after passing between the pressure rolls 19, 19', it is seen that the ink is pressed and distributed into the inter-fiber voids by the high nip pressure of the engaging rolls. Thus there is now less tendency for the ink to smear and setoff, i.e. transfer to an adjacent surface as for instance when stacking the cards. In addition, there is moisture transfer to the ink of a' portion of the film of moisture on the pressure rolls 19, 19, and drying of the moisture setting ink is initiated by this transfer of moisture. Since the pressure rolls have a uniformly hydrophilic surface, this moistened surface constitutes a barrier assuring prompt release of the ink from the pressure roll at the nip exit. The operation of the pressure dampening system in drying moisture-setting inks is a combination of these three effects: high nip pressure, moisture transfer, and ink release.

The dampening solution is normally aqueous since most moisture setting inks are dried by water. The dampening solution may contain other ingredients according to the type of pressure rolls used and the particular moisture setting ink. Typically the dampening solution is slightly acetic in character in order to continuously re-etch or rejuvenate the pressure rolls. Since most commercial moisture setting printing inks contain alkaline components, with a neutral solution these alkaline components of the ink would tend to make the surfaces of the rolls less hydrophilic. As an example, let it be assumed that the pressure rolls are either magnesium rolls or steel rolls plated with chrome. The printing ink is a moisture setting type having alkaline components, such as commercially available black. A dampening solution having a pH of about 5.5 has the following constituents:

Distilled water quarts 6 Methanol do 2 Phosphoric acid in dilute form ounces 3 Gum arabic do 2 The methanol reduces surface tension and also serves as Wetting agent, as does the gum arabic. The dilute phosphoric acid is a pH controller.

In the event that a pre-etched pressure roll is used, such as a magnesium pre-etched roll, the dampening solution may be neutral. The following is an example of a neutral dampening solution: distilled water and a 1% solution of glycol ether sold under the name Turgitol N.P.X. To this at times a defoamer may be added. This particular dampening solution is used for instance with a tinting ink where better results are obtained using glycol ether due to some ingredient in the ink which makes it bleed (i.e. blur) when the pH is too low. It is seen that the ingredients of the dampening solution can be varied according to the particular problem and conditions at hand.

The advantages of the invention are best appreciated by comparing it with the commonly used existing method of precipitating moisture setting inks by projecting saturated steam through nozzles or orifices in the direction of the printed web. In this method, condensation of steam on the surface of the web furnishes water to initiate the precipitation-drying process. The present pressure dampening system for drying moisture setting inks provides better contact of the moisture with the newly printed ink. This is because moisture is supplied under roll pressure, which contributes to improved permeation of moisture and the ink film and an increased rate of absorption of the ink solvent into the paper fibers. When saturated steam is used, the amount of moisture actually available for ink precipitation is governed by the quantity of steam that can be condensed on the surface of the ink film. The rate of condensation drops continuously as more steam is added because of a corresponding rise in the dew point of the ink film. The improved moisture contact provided by the pressure dampening system is particularly effective in drying heavy ink films. .With saturated steam, a skin of initially precipitated ink forms a barrier which tends to restrict further penetration of moisture into the underlying strata of the ink film. Substantial amounts of ink vehicle will thus remain in the ink. Precipitation being a reversible process, these quantities of vehicle can re-dissolve the dried surface layer of ink such that the ink is once again in the wet stage and capable of transferring as set-off and smear marks. With pressure dampening drying, sufificient moisture is applied directly to heavy ink films to effect their drying.

Another advantage of the invention is the independence from boundary layer effects. Since moisture is transferred in the liquid form, the pressure dampening system is not handicapped by boundary layer effects along the surface of a rapidly moving web. When using saturated steam, the access of steam to the web proper is limited by the boundary layer of air set up at high web speeds. Pressure roll dampening functions independently of boundary layer effects along the web. Thus the drying rate of moisture-setting ink films on a web in a high speed printing press is increased, and this is particularly advantageous with heavier ink films.

In summary it can be said that the invention increases the drying rate of moisture setting inks by the application of high roll pressure directly onto the ink film. Transfer and accumulation of ink on the pressure rolls is effectively prevented by providing a protective coating of dampening fluid to the surface of the pressure rolls. The surfaces of the pressure rolls can be kept hydrophilic by continuously re-etching the pressure rolls by special techniques to a degree permitting application of a uniform moisture layer without the formation of droplets. Moisture can be supplied to these pressure rolls by means of a dampening unit designed to permit control and regulation of the flow rate of dampening fluid to meet the particular requirements of the ink film to be dried. The pH of the dampening fluid can be controlled to effect continuous reetching of the pressure rolls. Drying of 'both thin and heavy films of most commercial printing ink is possible, using this method and apparatus, .at speeds at least up to 1,000 feet per minute.

Other ways of dampening the pressure rolls 19, 19 can be employed. For instance, moisture can be applied by a wick urged against the pressure roll by a leaf spring. A litho-style dampening system may be employed comprising a fountain roll revolving in dampening solution, a molleton covered ductor roll, a hard vibrator roller, and a molleton covered roll in contact with the pressure roll. A third variation is an endless belt running in contact with the pressure roll and about a fountain roll.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made thenein without departing from the spirit and scope of the invention.

What is claimed is:

1. The method of drying moisture-setting ink printed on fibrous web material having a surface including alternating peaks and inter-fiber voids, freshly printed ink in wet condition being deposited largely on the peaks of the fibrous web, comprising the steps of continuously coating at least one roll of a pair of substantially smooth metallic pressure rolls revolving substantially in contact with one another with a thin uniform film of acidic dampening solution in liquid form to continuously re-etch the surface of said one roll to maintain said surface hydrophilic, and

passing the freshly printed web between the pair of dampened pressure rolls to press substantially all the ink deposited on the peaks of the fibrous web into the inter-fiber voids to reduce the tendency to smear and set-off while simultaneously transferring a portion of the dampening solution onto the ink under pressure to initiate drying of the moisture-setting ink, complete drying occurring shortly after leaving the rolls and being solely by means of the dampening solution.

2. In a rotary card making machine for manufacturing cards from a fibrous web material having a surface including alternating peaks and inter-fiber voids, said machine including a print station for printing record forms onto the web with moisture-setting ink, freshly printed ink being deposited largely on the peaks of the fibrous web, and a cut-off station for cutting the web into unit lengths each having a printed form thereon, the print and cut-off stations each including a pair of rolls between which the web passes, the improvement comprising an ink drying station located between the print and cutoff stations,

said ink drying station including a pair of substantially smooth metallic rolls rotating in pressure contact against the web bearing freshly printed ink which is passed therebetween, and

means for continuously applying to the surface of at least one of said pressure rolls a thin uniform moisture film of slightly acidic dampening solution in liquid form,

whereby the surface of said one roll is continuously re-etched and maintained hydrophilic, and whereby substantially all the ink is pressed into the interfiber voids of the web to reduce the tendency to smear and set-off and simultaneously a portion of the moisture film is transferred onto the freshly printed ink under pressure to initiate drying thereof.

3. In a rotary card making machine for manufacturing cards from a fibrous web material having a surface including alternating peaks and inter-fiber voids, said machine including a print station for printing record forms onto the web with moisture-setting ink, freshly printed ink being deposited largely on the peaks of the fibrous web, and cut-off station for cutting the web into unit lengths each having a printed form thereon, the print and cut-off stations each including a pair of rolls between which the web passes, the improvement comprising an ink drying station located between the print and cut-off stations,

said ink drying station including a pair of metallic pressure rolls rotating substantially in contact with one another between which the web bearing freshly printed ink is passed, one of said rolls having a slightly etched hydrophilic surface,

a dampening roll having a moisture retaining surface rotating in contact with said one pressure roll for applying thereto a thin uniform moisture film of slightly acidic dampening solution in liquid form, and

means for supplying said dampening roll with said dampening solution,

whereby the surface of said one roll is continuously re-etched and maintained hydrophilic, and whereby substantially all the ink is pressed into the interfiber voids of the web to reduce the tendency to smear and set-off and simultaneously a portion of the moisture film is transferred onto the freshly printed ink under pressure to initiate drying thereof, subsequent drying being solely by means of the dampening solution.

4. In a rotary card making machine for manufacturing cards from a fibrous web material having a surface including alternating peaks and inter-fiber voids, said machine including a print station for printing record forms onto the web with moisture-setting ink and a cut-off station for cutting the web into unit lengths each having a printed form thereon, the print and cut-off stations each including a pair of rolls between which the web passes, the improvement comprising an ink drying station located between the print and cut-off stations,

said ink drying station including a pair of pressure rolls rotating substantially in contact with one another between which the web bearing freshly printed ink is passed,

a dampening roll having a moisture retaining surface rotating in contact with one of said pressure rolls for applying thereto a thin moisture film of dampening solution in liquid form, and

means for supplying said dampening roll with said dampening solution,

whereby the ink is pressed into the inter-fiber voids of the web to reduce the tendency to smear and setotf and simultanously a portion of the moisture film is transferred onto the freshly printed ink under pressure to initiate drying thereof, said means for supplying said dampening roll with dampening solution including a spray nozzle directed at said dampening roll, and a metering roll for regulating the amount of moisture retained by the moisture retaining surface of said dampening roll.

References Cited by the Examiner UNITED STATES PATENTS 1,364,043 12/1920 Dixon 117-36.4 2,157,387 5/1939 MacArthur 34-9 X 2,231,666 2/1941 Golber 101-147 2,244,103 6/1941 Erickson et al. 101-416 X 2,250,516 7/1941 Wood 101-149.2 2,275,521 3/1942 Gessler 34-9 X 2,518,607 8/1950 Erickson 101-426 FREDERICK L. MATTESON, Primary Examiner.

JOHN J. CAMBY, Examiner. 

1. THE METHOD OF DRYING MOISTURE-SETTING INK PRINTED ON FIBROUS WEB MATERIAL HAVING A SURFACE INCLUDING ALTERNATING PEAKS AND INTER-FIBER VOIDS, FRESHLY PRINTED INK IN WET CONDITION BEING DEPOSITED LARGELY ON THE PEAKS OF THE FIBROUS WEB, COMPRISING THE STEPS OF CONTINUOUSLY COATING AT LEAST ONE ROLL OF A PAIR OF SUBSTANTIALLY SMOOTH METALLIC PRESSURE ROLLS REVOLVING SUBSTANTIALLY IN CONTACT WITH ONE ANOTHER WITH A THIN UNIFORM FILM OF ACIDIC DAMPENING SOLUTION IN LIQUID FORM TO CONTINUOUSLY RE-ETCH THE SURFACE OF SAID ONE ROLL TO MAINTAIN SAID SURFACE HYDROPHILIC, AND PASSING THE FRESHLY PRINTED WEB BETWEEN THE PAIR OF DAMPENED PRESSURE ROLLS TO PRESS SUBSTANTIALLY ALL THE INK DEPOSITED ON THE PEAKS OF THE FIBROUS WEB INTO THE INTER-FIBER VOIDS TO REDUCE THE TENDENCY TO SMEAR AND SET-OFF WHILE SIMULTANEOUSLY TRANSFERRING A PORTION OF THE DAMPENING SOLUTION ONTO 